Fuse Tuning?! This is a trial set for high-efficiency fuse tuning. Fuse tuning...? Really? This is a single trial item to see if you notice a change in sound, especially with your navigation system. If you like it, consider trying it in your car too! These are high-quality fuses made by a domestic OEM manufacturer, with improved conductivity, electrical performance, static electricity reduction, and special processing. *To counter imitations and low-quality products, some products undergo special processing to further enhance performance. This may appear as stains or discoloration, but it's due to the processing agent and does not affect performance. This processing technology is something that copy products and businesses that primarily deal in copy products cannot replicate. This is a trial set. I've listed it because the effect of replacing the fuse is easy to notice with a navigation system. If you like it, please consider the set product (lol). Users of Carrozzeria, Panasonic, and Kenwood navigation systems have tested this. Many have confirmed improvements in sound quality and sound pressure. Some have even lowered their usual volume because the sound became louder (lol). Please check your navigation system's manual and specify whether you need a low-profile fuse or a mini fuse, and the amperage (10A or 15A). This is a trial, so it's one fuse and includes shipping. I will also be starting to sell a 6-piece set of "Everyone's Tuning Fuses" separately. Please try them if you're interested. Please understand that this is a DIY product made on my days off, and I appreciate your purchase. We will ship them sequentially after confirming payment. Thank you very much! We have received many reports of imitations and counterfeit products from repeat customers. Please be careful and review the product descriptions and ratings. #antistaticsystem's static electricity removal tuning parts are here.